Implant Screw (TC4)

   Implant Screw Description:

Mechanical specs and process parameters:

Thread valley bottom/load contact surface roughness: Ra ≤0.2μm, differentially control in designated areas.
Bottom corner/tool radius: ≤0.10 mm for micro tool machining for small-sized and sharp turning structures.
Thread specifications and tolerances: ISO/custom threads, precision according to customer drawings.
Key dimensions SPC: SPC controls diameter, pitch, taper, drive profile, shoulder transition, and can provide Cp/Cpk reports.
Micro texture orientation: Customize texture direction, pitch, depth, and coverage area.
Surface engineering: sandblasting, acid etching, composite process, set up parameters according to the target bone bonding speed.
Material: Ti-6Al-4V ELI, medical stainless steel, heat treated, aging state executed as specified.
Traceability system: Raw material furnace number, bar batch number, CNC machining batch, finishing batch, final inspection batch, full process batch number traceability.

Implant screw feature application + performance + compatibility:

Functional application: Suitable for long-term implantation of bone fixation, implant connection, and modular component locking. Support disposable implant screws, detachable attachment implant screws, and system platform matching implant screws
Key performance: Geometry and valley radius are optimized according to stress paths, reducing local stress concentration and improving high cycle fatigue life. Controllable micro texture + surface activation to enhance initial osseointegration speed and interface stability. The torque displacement curve, pull-out force, and fatigue life can be aligned with ASTM/ISO/customer internal standards.
Compatibility and adaptation: It can be reverse engineered based on existing platforms to achieve complete compatibility of the connection interface, only upgrading materials and surface engineering. Support geometric and surface joint operations based on customer CAD/FEA models to synergistically optimize stress distribution and bone contact area. The tolerance zone, driving form, and connection profile are all defined according to the customer platform, making it easy to directly match with existing instruments and implant systems.

Johoty value:

Deep microfabrication capability: Mature application of Ra ≤0.2μm thread valley and contact surface microfabrication technology. Stable control of tool radius ≤0.10mm under mass production conditions to ensure consistency of small-sized features.
Engineering oriented surface and stress design: Micro texture orientation and texture parameters can be defined according to engineering goals, rather than fixed standard textures. Based on customer FEA data, optimize thread geometry and transition zone stress distribution to reduce fatigue fracture risk.
Manufacturing quality and data transparency: Implement SPC for critical dimensions and provide Cpk data. Traceability from material furnace number to implant screw batch supports medical device regulations and quality system requirements.
Flexible customization and engineering docking: Supports migration from small batch trial production to the same process platform for implant screw mass production, with parameters that can be smoothly scaled up. Engineers can communicate directly with engineers and iterate design around drawings, tolerances, surface call outs, and test indicators.

Optimization of microfabrication technology: precise tool radius control:

Challenges: In high-precision medical device or implant screw manufacturing, the controllability of surface fine texture and tool radius are crucial for microfabrication. Any small error may affect the overall quality and fatigue life of the product.

Johoty solutions: Using five-axis and six-axis microfabrication equipment, Johoty precisely controls the bottom of the thread and the contact surface. We can provide surface quality for implant screws with Ra ≤ 0.2μm. The micro texture orientation of surface microstructure can effectively reduce stress concentration. To avoid fatigue fractures caused by surface defects and extend the service life of the implant screw.

Bone Fusion Acceleration and Stress Optimization Design:

Challenges: Implant screw: Surface activation treatment can effectively improve the binding speed of bone tissue during the process of osseointegration. Engineers often require improved osseointegration to ensure optimal stress distribution of the implant screw.

Johoty solutions: Advanced surface activation to improve bone integration speed and reduce postoperative adverse reactions. The optimized stress distribution design makes the implant screw safer. We can avoid fatigue damage during long-term use and ensure the stability and reliability of the implant screw.

Total Quality Control and Traceability Management:

Challenges: Medical devices or implant screws require high material traceability and critical dimension control. Engineers often focus on the traceability of every implant screw. And the dimensional accuracy of each implant screw to meet the strict quality standards of the European and American markets.

Johoty solutions: Strictly implement material batch number traceability management to ensure traceability of raw materials and production processes for each implant screw. Through SPC, Johoty ensures the accuracy of critical dimensions and conducts strict quality inspections on each batch of implant screws. Minimize production errors to ensure that each implant screw has of the highest quality.

Micro geometric controllability of the thread bottom of Implant screw significantly reduces fatigue fracture:

Engineering Challenges:

The long-term failure of spine, trauma, and dental implant screws is almost always related to fatigue cracks at the bottom of the thread or geometric transition. Many designs with nominal stress in FEA are safe. However, the roughness of the valley bottom, the direction of knife marks, and micro notches on the actual implant screw will consume the theoretical safety margin.

Johoty’s solutions and advantages:

The valley bottom and contact surface of the thread with Ra ≤ 0.2μm:

• Lowering the surface notch size to a much smaller scale than the microstructure of the material itself can reduce the impact of surface defects on fatigue strength.
• Under high cycle fatigue, the initiation of cracks shifts from being dominated by surface notches to being dominated by the overall stress state and intrinsic defects of the material. This can greatly reduce early cracking cases.

Micro machining equipment with tool radius ≤ 0.10 mm:

• The valley corner profile, transition radius, and flare transition zone can be precisely defined during the design phase. Design without being constrained by the conventional tool radius in reverse.
• Satisfy the minimum safe fillet and accurately transfer the stress concentration factor Kt assumed by FEA to the implant screw as much as possible. Instead of being magnified by random knife marks and excessive cutting during processing.

Micro texture orientation controllable + stress distribution optimization:

• Control the angle between the tool path and the direction of the maximum principal stress to avoid the formation of guided tool marks in the same direction as the principal stress. Suppress the rapid and stable propagation of cracks in surface grooves from the source.
• Arrange horizontal or intersecting textures in the transition zone of the neck and the smallest cross-sectional threaded ring. Extend the lifespan range of crack initiation and early propagation in fracture mechanics.

Results:

• The dispersion of the S-N curve at the low lifetime end significantly narrows, and the design safety factor does not need to be excessively raised by extreme cases.
• Allowing materials with smaller diameters or higher strength levels under the same safety objectives, leaving space for structural and surgical design.
• The sample size of fatigue testing is controllable, the statistical confidence is improved, and the failure analysis can be more closed.

Functional surface + micro texture orientation, Implant screw for predictable osseointegration:

Engineering Challenges:

• Can the speed of osseointegration be predicted?
• Is the interface micro motion under dynamic load within the design window?
• Can the interface behavior of cortical/cancellous bone and different anatomical sites be designed and replicated, rather than solely relying on the surgeon’s experience and individual differences?

Johoty’s solutions and advantages:

Surface zoning for distinguishing functions:

• Thread valley bottom/mechanical pressure bearing surface Ra ≤ 0.2 μ m, micro texture+surface activation is performed in the bone contact area.
• The high stress valley and mechanical contact area maintain extremely low Ra, prioritizing fatigue strength and contact fatigue.
• The actual area in contact with bone can be treated with controllable micro texture orientation and surface activation. Both achieve spatial decoupling of mechanical and biological functions on the same component.

Micro texture orientation is controllable:

• By adjusting the relationship between texture direction, thread axis, and load path, priority “bite” and anti slip ability can be provided in the interface shear direction.
• In the area of cancellous bone, a combination of radial/helical textures can be designed to increase early micro mechanical interlocking and suppress micro motion; In the cortical bone area, lower height and directional textures can be selected to balance bone stress shielding and interface stiffness.

Surface activation：

• Improve surface free energy and wettability, enabling faster and more uniform initial adsorption of plasma proteins and bone matrix proteins.
• Provide a stable starting point for spreading, subsequent cell adhesion, and matrix deposition. Transforming osseointegration from a random event to a process controlled dynamic process.

Results:

• The dispersion of ISQ, pull-out force, and micro motion level between batches decreases in the early stage after implantation. Engineers can set clearer boundary conditions for early load-bearing.
• Engineers can form modular designs by combining Ra, texture direction, and activation schemes for different bone types and sites. Instead of trial and error for every new model from scratch.
• The sample size of the experimental design is reduced, the interface failure modes are clearer, and the risk assessment is quantifiable.

Contact interface friction can be designed, and the Implant screw reduces the risk of looseness, wear, and corrosion:

Engineering Challenges:

The long-term problems of multi-component nail rod systems, plate screw systems, and adjustable connectors often do not lie in the implant screw body. But the following issues directly affect the torque preload correlation, long-term stability, and corrosion product risk:

• Screw head plate/gasket contact surface fretting.
• The pre tightening force of the screw connecting rod clamping interface attenuates.
• Debris and localized corrosion caused by micro motion wear.

Johoty’s solutions and advantages:

Contact surface Ra ≤0.2μm + controllable micro texture orientation:

• In interfaces that require high stability preload, low Ra+specific directional textures can be used. The friction coefficient remains stable within the design range, rather than being determined by random knife marks.
• Convert the friction coefficients from FEA and analytical calculations into manufacturing constants with minimal differences between batches on a real implant screw. Improve the torque preload model reliability.

Stress distribution optimization to avoid local contact peaks:

• When the tool radius is ≤0.10 mm and the contact surface is microformed, the correspondence between the actual contact area and the nominal contact area is closer to the design value. Weakening the micro fatigue and local plasticity caused by point like peaks.
• Under multiple loading unloading cycles, plastic accumulation in the contact area can be suppressed. Reduce fretting and micro delamination from the perspective of tribalogy.

Indirect inhibition of corrosion and abrasive particle formation:

• Due to the controlled micro motion amplitude and contact peak stress, the amount of abrasive particles formed on the metal metal interface is reduced. The frequency and area of oxide film damage decrease, and the driving force for local corrosion weakens.
• Higher long-term torque retention rate, reduced noise and loosening cases during clinical follow-up, and reduced uncertainty related to corrosion.

Results:

• The dispersion band of assembly torque vs disassembly torque narrows between different batches and LOTs. Can serve as a quantitative basis for DOE and process confirmation.
• The long-term stability of plate screw and nail rod systems has shifted from relying on the operator’s hand feel to relying on validated interface frictional design.

Implant screw critical dimension SPC + material batch number traceability, supporting engineering decision-making and life failure management:

Engineering Challenges:

• Are dimensions, tolerances, and material properties truly valid in batch production?
• Once on-site failure occurs, can it be traced back to batch, process drift, or material issues instead of relying solely on experience attribution?

Johoty’s solutions and advantages:

Key dimension SPC:

• Implement Cpk index driven SPC for thread related outer diameter, root diameter, pitch, flange angle, coaxiality, and head geometry. Ensure that the size distribution remains stable in the middle area of the design tolerance zone for a long time.
• Engineers can obtain a high degree of consistency between the dimensions used in FEA/analytical models and the statistical distribution of real parts. The impact of extreme outliers on fatigue, safety margins, and assembly behavior can be clearly quantified, rather than just scratching the head.

Material batch number traceability:

• Each implant screw can be traced back to a specific material batch number and heat/surface treatment batch. Support targeted metallographic, electrochemical, and mechanical retesting when needed.
• When isolated fracture or abnormal corrosion occurs, the failed part can be compared with samples of the same batch number and process window. No need to blindly investigate within the entire implant screw family.

Closed loop of process performance failure:

• Combining SPC data with material batch information provides the basis for constructing causal diagrams of process parameters geometric deviations fatigue/interface performance.
• Design changes can be based on quantitative evidence to adjust safety factors, tolerance strategies, and test plans.

Results:

• Design validation, process confirmation, and revalidation are supported by reusable data assets to reduce repetitive testing.
• It is easier to demonstrate the consistency and risk control level of the product.
• Not only does it sell an implant screw, but it also provides a verifiable, traceable, and iterative engineering system.